Reaction product of 2 3-dibromopropanol and phosphorus pentoxide

ABSTRACT

THE PRODUCT OF THE REACTION OF 2.3-DIBROMOPROPANOL, PHOSPHORUS PENTOXIDE IN AN AMOUNT SUFFICIENT TO PROVIDE THEREIN FROM 1 TO 2 ATOMS OF PHOSPHORUS PER MOLECULE OF 2.3-DIBROMOPROPANOL, EITHER ADDITIONAL PHOSPHORUS PENTOXIDE, PHOSPHORIC ACID OR POLYPHOSPHORIC ACID IN AN AMOUNT TO PROVIDE WITH THE FIRST MENTIONED PHOSPHORUS PENTOXIDE, A TOTAL OF 3 TO 25 ATOMS OF PHOSPHORUS PER MOLECULE OF 2.3-DIBROMOPROPANOL AND SUFFICIENT FREE WATER, IF NECESSARY, TO PROVIDE WITH ANY COMBINED WATER THAT MAY BE PRESENT, A WATER CONTENT OF 0.8 MOLECULE THEREOF FOR EACH PHOSPHORUS ATOM IN THE ADDITIONAL PHOSPHORUS PENTOXIDE, THE PHOSPHORIC ACID OR THE POLYPHOSPHORIC ACID, IS DISSOLVED IN WATER WITH SUFFICIENT AMMONIA TO ADJUST THE PH OF THE RESULTING SOLUTION TO WITHIN THE RANGE FROM 5 TO 8, WHEREBY TO PROVIDE A WATER-SOLUBLE FLAME RETARDANT FOR TEXTIEL FIBERS OR FABRICS. THE REACTION MIXTURE MAY FURTHER INCLUDE A MAXIMUM OF 1 MOLECULE OF UREA FOR EACH 2 ATOMS OF PHOSPHORUS IN THE TOTAL NUMBER OF THE LATTER. THE SOLUTION FOR IMPARTING FLAME REATRDING PROPERTIES TO TEXTILE MATERIALS MAY INCLUDE A FIRE RETARDANT SALT, SUCH AS AMMONIUM PHOSPHATE, ALONG WITH THE STATED REACTION PRODUCT PROVIDED THAT THE LATER CONSTITUTES AT LEAST 10 WT. PERCENT OF THE TOTAL SOLIDS CONTENT OF THE SOLUTION.

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'United '8 3,644,597 REACTION PRODUCT F 2,3-DIBROMOPROPANOL ANDPHOSPHORUS PENTOXIDE Abraham S. Endler, Flushing, N .Y., assignor toApex Chemical Co., Inc., Elizabethport, NJ. N0 Drawing. Filed Jan. 28,1969, Ser. No. 794,805 Int. CI. 01715 9/08; C09k 3/28 US. Cl. 260-933 9Claims ABSTRACT OF THE DISCLOSURE molecule of 2,3-dibromopropanol andsufficient free water,

if necessary, to provide, with any combined water that may be present, awater content of 0.8 molecule thereof for each phosphorus atom in theadditional phosphorus pentoxide, the phosphoric acid or thepolyphosphoric acid, is dissolved in water with sufficient ammonia toadjust the pH of the resulting solution to within the range from to 8,whereby to provide a water-soluble flame retardant for textile fibers orfabrics. The reaction mixture may further include a maximum of 1molecule of urea for each 2 atoms of phosphorus in the total number ofthe latter. The solution for imparting flame retarding properties totextile materials may include a fire retardant salt, such as ammoniumphosphate, along with the stated reaction producfprovided that thelatter constitutes at least 10 wt. percent of the total solids contentof the solution.

This invention relates generally to flame retardants for application totextile fibers or fabrics, which are hereinafter generally referred toas textile materials, and more particularly to water-soluble, grganieflame re tar ts.

A number of ammonium salts of inorganic acids are known to be effectiveas flame retardants when applied in sufficient proportion to textilefabrics. One general disadvantage of all of these salts is that theytend to crystallize on the surface of the textile fibers, or internally,creating either undesirable stiffness or an undesirable whitish powderysurface appearance.

Many organic salts do not crystallize in this manner, and do not causethese undesirable etfects, but unfortunately organic salts in general donot exhibit any flame retardant action. Ammonium salts of alkyl acidesters of phosphoric acid show a slight flame retardant action oncellulosic fibers, provided that the alkyl groups in the ester do notcontain excessive proportions of carbon and hydrogen. Thus, partialesters of phosphoric acid with ethylene glycol, glycerol, and otherglycols are known to have some desirable fire retardant properties.Unfortunately a much higher'weight percent add-on of these esters isneeded than with the common inorganic fire retardant salts, such asammonium phosphate.

The use, as a flame retardant, of the ammonium salt of the ester of2,3-dibromopropanol with phosphoric acid, that is, the ammonium salt of2,3-dibromopropylphosphoric ester, has been disclosed in priorliterature. Although such compound is an effective flame retardant anddoes not crystallize either on the surface of the treated textilefibers, or internally therein, it is relatively costly, as compared withammonium phosphate or ammonium sulfamate, by reason of the high cost ofthe 2,3-

3,644,597 tnted Pele. 22, 1972 dibromopropanol constituting the majorproportion there of, and further it is disadvantageously characterizedby a sticky or tacky feel and a brownish color. The reported ammoniumsalt of 2,3-dibromopropylphosphoric ester is also only sparingly solublein water which leads to difficulties in its application, as a flameretardant, to textile fibers or fabrics.

Accordingly, it is an object of this invention to provide relativelylow-cost flame retardants of almost water-white color that can beapplied to a wide variety of textile materials, either in the form offibers or fabrics, to afford thereto effective flame-retardingproperties without unduly affecting the feel of the fabric and withoutcrystallizing or otherwise contributing to an undesirable appear ance ofthe fabric.

A further object is to provide flame retardants having the foregoingcharacteristics and which are water-soluble for ease of application totextile materials.

Still another object is to provide flame retardants that are aseffective as the mentioned ammonium salt of. 2,3-dibromopropylphosphoric ester and similarly do not crystallize, butwhich are free of the undesirable characteristics of the known compound,that is, the tacky feel, brownish color and poor solubility in water ofthe latter.

In accordance with this invention, the foregoing objects are achieved byreacting 2,3-dibromopropanol with phos phorus pentoxide in an amountsufficient to provide at least 1 atom of phosphorus in such phosphoruspentoxide per molecule of 2,3-dibromopropanol, and with eitheradditional phosphorus pentoxide, phosphoric acid or polyphosphoric acidin an amount sufiicient to provide, with the first mentioned phosphoruspentoxide, at least 3 atoms of phosphorus per molecule of2,3-dibromopropanol, the water content of the reaction mixture beingadjusted to provide approximately 0.8 moleculeof combined and/or freewater for each phosphorus atom in the additional phosphorus pentoxide,phosphoric acid or polyphosphoric acid, and by dissolving the resultingreaction product in water with suflicient ammonia to adjust the pH ofthe solution to within the range from 5 to 8.

Where the 2,3-dibromopropanol is reacted with phosphorus pentoxide and115% polyphosphoric acid (also known as triphosphoric acid) the latterhas 0.8 molecule of combined water per atom of phosphorus therein, sothat no adjustment of the water content of the reaction mixture isrequired. Where the 2,3-dibromopropanol is reacted only with phosphoruspentoxide, free water is added to the reaction mixture to provide the0.8 molecule of water per atom of phosphorus in the phosphorus pentoxideemployed in excess of that required to furnish at least 1 atom ofphosphorus per molecule of 2,3-dibromopropanol. Where the2,3-dibromopropanol is reacted with phosphorus pentoxide and phosphoricacid, which contains 15%, by weight, of free water and further 1.5molecules of combined water per. atom of phosphorus in the phosphoricacid, the necessary adjustment of the total water content of thereaction mixture can be achieved by employing partly phosphoruspentoxide, which has no combined water, and partly 85 phosphoric acid toprovide the phosphorus atoms in excess of the phosphorus atoms furnishedin the form of phosphorus pentoxide to make available at least 1 atom ofphos phorus for each molecule of 2,3-dibromopropanol. Similarly, wherethe reaction mixture contains 2,3-dibromopropanol, phosphorus pentoxideand polyphosphoric acid, which is also known as superphosphoric acid andcontains 1.23 molecules of combined water per atom of phosphorustherein, the necessary adjustment of the water content is effected byemploying an excess of phosphorus pentoxide beyond that required toprovide at least 1 atom of phosphorus per molecule of2,3-dibromopropanol. 4 Although the above general description of thereaction 3 mixture according to this invention states that the amount ofphosphorus pentoxide provided therein, in the first instance, issuflieient to provide at least 1 atom of phos whorus per molecule of2,3dibromopropanol in the reaction mixture, the amount of phosphoruspentoxide included for the foregoing purpose preferably should not thatwhich provides 2 atoms of phosphorus in the form of phosphoruspentoxide) per molecule of 2,3-dibromopropanol, excessive amounts ofphosphorus in the form of phosphorus pentoxide will lead to undesirabledarkening of. the reaction product. Of course, the foregoing limitationon the maximum amount of phosphorus pentoxide in the reaction mixtureonly applies to that provided for furnishing phosphorus in the form ofphosphorus pentoxide and not to the phosphorus pentoxide that may beincluded in the reaction mixture with free water to provide theequivalent of 115% polyphosphoric acid, nor to the phosphorus pentoxidethat may be employed with phosphoric acid or with 105% polyphosphoricacid to adjust the water content to the equivalent g of 115%polyphosphoric acid (that is, 0.8 molecule of water per atom ofphosphorus).

1f the amount of phosphorus pentoxide in the reaction mixture is lessthan that required to provide 1 atom of phosphorus in the form ofphosphorus pentoxide per molecule of 2,3-dibromopropanol, as specifiedabove, the reaction will not be complete.

Further, although the total number of phosphorus atoms. provided in theform of phosphorus pentoxide and otherwise, may substantially exceed 3atoms of phosphorus per molecule of 2,3-dibromopropanol. preferably nomore han atoms of total phosphorus per molecule of 2,3 dibromopropanolare included in the reaction mixture. Beyond the foregoing maximum ratioof phosphorus atoms to 2,3-dibromopropanol molecules in the reactionmixture, the flame retardants produced therefrom have an increasedtendency to crystallize when applied to textile fibers or fabrics andthe advantages inherent in the organic nature of the product arediminished.

The amount of water in which the described reaction product is dissolvedis selected to preferably provide the resulting solution with solidscontent of the reaction product that is preferably in the range fromabout to W1. percent.

Such solution with ammonia added thereto sufficient to adjust the pH towithin the range from 5 to 8, is readily soluble or dilutable withfurther water for application to a wide variety of textile fibers orfabrics so as to impart flame retarding properties thereto with a dryaddon of the product of this invention in the range from to 30% based onthe weight of fiber or fabric.

The reaction mixture from which products according to this inventionresult may further include urea in limited amounts that do not exceed 1molecule of urea for e ch 2 atoms of the total phosphorus atoms providedin the reaction mixture. The inclusion of urea in the reaction mixtureis found to improve the color of the reaction product and also tofurther reduce the tackincss of the dried flame retardant on the textilefibers or fabrics. However, similar desirable characteristics can beachieved without urea in the reaction mixture if the reactiontemperature is carefully controlled, for example, so as to be ma ntainedin the range between about 80 and 100 C.

The flame retardants according to this invention may be applied alone totextile materials, as previously indi cated, or in admixture with one ormore inorganic salts, such as, ammonium phosphate, ammonium bromide,ammonium sulfamate, ammonium sulfate and ammonium chloride, so as tosubstantially improve the properties of the finish imparted by theinorganic salts. The mentioned inorganic flamcproofing salts tend toform whitish, powdery surface deposits when applied in amounts suffeientto impart substantial flame retarding properties to textile materials.The foregoing is particularly noted in the case of the treatment oftextile fibers or fabrics which do not readily absorb water, such asnylon, olyester, spandex, triacetate and other so-called hydrophobicllbcrs. However, if even such hydrophobic fibers, or textile labritrsmade therefrom, are t eated with mixtures of one or more of theinorganic salts, such as, ammonium phosphate, ammonium bromide, ammoniumsulfainate, ammonium sulfate or ammonium chloride, and a water-solubleflame. retardant according to this invention which constitutes at least10 wt. percent of the total solids, the crystalline powdery appearanceof the treated fabric is substantially eliminated, and the tendency ofthe inorganic salts to be come dislodged from the fabric by shaking orrubbing is also greatly reductd,

An important advantage of the flame retardants accord ing to thisinvention is that they exhibit the mentioned desirable properties whenapplied to a wide variety of textile fibers and to woven, knitted ornon-woven fabrics produced from such fibers. Thus, in addition tofabrics of the previously mentioned hydrophobic fibers, the fireretardants according to this invention may be advantageously applied,either alone or in admixture with in-- organic salts, to fabrics ofcotton, rayon, cellulose acetate and blends thereof either with eachother or with the named hydrophobic fibers.

The invention will now be further described with rel erence to thefollowing specific examples which at e merely illustrative:

EXAMPLE. 1

218 grants of 2,3-dibromopropanol (l grarnmolec'ular weight) aredisposed in a flask equipped with a stirrer and thermometer, and 172grants of 115% polyphosphoric acid (containing 2 gram-atomic weights ofphosphorus) are added to the 2,3-dibromopropanol. The contents of theflask are mixed for 15 minutes while cooling the flask contents with anexternal water bath, as required, to we vent a temperature rise aboveC., vhercupon. over a period of 30 minutes, 71 grams of phosphoruspentoxide (containing 1 gram-atomic weight of phosphorus) are addedportionwise to the flask contents while external. cooling is continued,as required, to maintain the reaction mixture temperature between 80 andC. After all of the phosphorus pentoxide has been added, the reactionmixture is further stirred for 2 hours at a, temperature between 80 and90 C., and at the end 01' such time all of the phosphorus pentoxide hasdissolved and the resulting product is a clear amber liquid.

In the above described reaction mixture, there is i atom of phosphorusin the form of phosphorus pentoxide per molecule of 2,3-dibromopropanol,and 2 atoms of: phosphorus in the polyphosphoric acid per mole-- cule of2,3-dibromopropanol, that is, a total of 3 atoms of phosphorus permolecule of 2,3-dibromopropanol. Further, the only water in the reactionmixture is the combined water in the 115% polypltosphoric acid which ispresent in the ratio of 0.8 molecule of water per atom of phosphorus inthe polyphosphoric acid.

The reaction product in the form of a clear amber liq aid is poured ontoone-half its own weight of crushed ice, and aqua ammonia is slowly mixedin until the pH of the mixture is between 5 and 8. The resulting liquidis found to have between 50 and 55 wt. percent solids dissolved therein.

EXAMPLE 2 218 grams of 2,3dibromopropanol (1 gram-molecular weight) and516 grams of 115% polyphospl'ioric acid (containing 6 gram-atomicweights of phosphorus) are mixed together in a flask equipped with a.stirrer and thermometer. After mixing for 10 minutes, during which. timethe temperature of the flask contents rises to about. 40 C. and thedibromopropanol dissolves completely in the polyphosphoric acid, gramsof urea (3 gram-mo1ecular weights) are added to the flask contents andthe latter are warmed to 100 C. and mixed at the latter temperature for15 minutes to completely dissolve the urea. Thereupon, 142 grams ofphosphorus pentoxide (containing 2 gram-atomic weights of phosphorus)are added portionwise to the flask contents over a period of 30 minutes,with the temperature being maintained between 100 and 110 C. during suchaddition. The reaction mixture is then stirred for 1 hour at atemperature between 100 and 110 C., whereupon, the reaction product ispoured onto onehalf its weight of crushed ice and concentrated aquaammonia is added slowly with mixing until the pH of the resultingsolution is adjusted to within the range from to 8. The that solution isalmost colorless and somewhat turbid with a solids content of about 50'wt. percent, but an almost clear solution results when it is furtherdiluted with Water.

In the reaction mixture described in this example, there are 2 atoms ofphosphorus in the form of phosphorus pentoxide per molecule of2,3-dibromopropanol, a total of 8 atoms of phosphorus per molecule of2,3-dibromopropanol, and the only water content is the combined water ofthe 115% polyphosphoric acid which is thus present in the ratio of 0.8molecule of water per atom of phosphorus in the 115% polyphosphoricacid. Further, the urea is present in the reaction mixture in the ratioof 3 molecules of urea to 8 atoms of phosphorus.

EXAMPLE 3 Using a procedure similar to that of Example 2, 218 grams of2,3-dibromopropanol (1 gram-molecular weight) are reacted with 1548grams of 115% polyphosphoric acid (containing 18 gram atomic weights ofphosphorus) and then with 120 grams of urea (2 gram-molecular weights)and finally with 142 grams of phosphorus pentoxide (2 gram-atomicweights of phosphorus).

Such reaction mixture is seen to contain 2 atoms of phosphorus in theform of phosphorus pentoxide per molecule of 2,3-dibromopropanol, atotal of 20 atoms of phosphorus per molecule of 2,3-dibromopropanol, andonly 2 molecules of urea for 20 total atoms of phosphorus. Further,since the only water is that present as combined water in the 115%polyphosphoric acid, there are 0.8 molecule of water for each atom ofphosphorus present as the polyphosphoric acid.

The product of the above reaction mixture is mixed with crushed ice andconcentrated aqua ammonia to provide a final product which is asubstantially clear liquid having a pH between 5 and 8 and a solidscontent of about 50 wt. percent. Such liquid is further dilutable withwater to yield a clear solution.

EXAMPLE 4 218 grams of 2,3-dibromopropanol (1 gram-molecular weight) aremixed in a flask having a stirrer and thermometer with 115.5 grams of85% phosphoric acid (containing 1 gram-molecular weight of. 100%phosphoric acid, which supplies 1 gram-atomic weight of phosphorus, and0.94 gram-molecular weights of free water in addition to the 1.5gram-molecular weights of Water provided as combined water in the 100%phosphoric acid). Using external cooling as needed to maintain thetemperature of the flask contents at 80 to 90 C., there are added, inportions, to the flask contents 213 grams of phosphorus pentoxide(representing 1% gram-molecular weights which contain 3 gram-atomicweights of phosphorus). After one-half of the mentioned quantity ofphosphorus pentoxide has been added, the mixture is stirred for 1 hourso as to dissolve all of the previously added phosphorus pentoxide. Then120 grams of urea (2 gram-molecular weights) are added to the flaskcontents which are stirred at 100 C. for minutes to dissolve the urea.The remaining half of the phosphorus pentoxide is then added, inportions, while holding the temperature at 100 to 110 C. When all of thephosphorus pentoxide has been thus added, the mixture is stirred for 1hour more, whilethe temperature is held in the range between 100 and110" C. The resulting reaction product is mixed with crushed ice andneutralized with aqua ammonia to have a pH between 6 5 and 8, yielding ahazy liquid with a solid content of about 50 wt. percent which isdilutable with water to provide faintly hazy solutions.

In this example, the reaction mixture has 1 atom of phosphorus suppliedin the form of phosphoric acid and 3 atoms of phosphorus supplied in theform of phosphorus pentoxide, that is, a total of 4 atoms of phosphorus,per molecule of 2,3-dibromopropanol. The 2.44 gram-molecular Weights ofwater (1.5 gram-molecular weights of free water and 0.94 gram-molecularweights of combined water) contained in the phosphoric acid combinedwith the 1 gram-atomic weight of phosphorus contained in the phosphoricacid and with 2 of the gram-atomic weights of phosphorus supplied in theform of phosphorus pentoxide, to provide the desired ratio (2.44:3) of0.8 molecule-of water per atom of phosphorus in addition to theremaining 1 atom of phosphorus in the form of phosphorus pentoxide whichis available for each molecule of 2,3-dibromopropanol.

EXAMPLE 5 218 grams of 2,3-dibromopropanol (1 gram-molecular weight) aredisposed in a flask equipped with a stirrer and thermometer, and 71grams of phosphorus pentoxide (containing 1 gram-atomic weight ofphosphorus) are added thereto. The flask contents are stirred at 80 toC. for 2 hours, and then 18 grams of Water in the form of chopped ice(1- gram-molecular weight) are added thereto. Thereafter, over a periodof 1 hour, 89 grams of phosphorus pentoxide are added to the flaskcontents followed by the addition of 18 grams of chopped ice (1gram-molecular weight of water) and then by the gradual addition of afurther 89 grams of phosphorus pentoxide over a period of 1 hour. The178 grams of phosphorus pentoxide thus added contain an additional 2.5gram-atomic weights of phosphorus. Thus, the reaction mixture contains 2gram-molecular weights of water which, with respect to 2.5 of thegram-atomic weights of phosphorus provided in the form of phosphoruspentoxide, gives the desired 0.8 ratio of molecules of water to atoms ofphosphorus, while 1 atom of phosphorus in the form of phosphoruspentoxide remains for each molecule of 2,3-dibromopropanol. Further, theratio of total atoms of phosphorus per molecule of 2,3-dibromopropanolis 3.5:1.

After the final additions to the reaction mixture, the latter is stirredfor 2 hours at 80 to 100 C., whereupon the reaction product is pouredonto one-half its own Weight of chopped ice and neutralized withsufiicient concentrated aqua ammonia to provide a final product with apH in the range between 5 and 8 and a solids content of approximately 50wt. percent. Such final product is a clear solution with a faint yellowcolor.

EXAMPLE 6 218 grams of 2,3-dibromopropanol (1 gram-molecular Weight) aremixed, for 1 hour at 80 C., with 932 grams of polyphosphoric acid(containing 10 gram-atomic weights of phosphorus and approximately 12.3grammolecular weights of combined water). Then 384 grams of phosphoruspentoxide (containing about 5.4 gramatomic weights of phosphorus) areadded slowly to the reaction mixture while holding the temperaturethereof between 80 and 100 C., whereby the 12.3 gram-molecular weightsof water and the 15.4 gram-atomic weights of phosphorus in mixtureresult in the desired ratio of 0.8 molecule of water per atom ofphosphorus. grams of urea (3 gram-molecular weights) are added to thereaction mixture which is then further mixed for lhour at 100.C.,followed by'the addition of 142 grams of phosphorus pentoxide(containing 2 gram-atomic weights of phosphorus) and stirring of thefinal reaction mixture for 2 hours at 80 to 100 C, It will be seen thatthe final reaction mixture contains a total of 17.4 atoms of phosphorusper molecule of 2,3-dibrornopropanol, with 2 atoms of phosphorus in theform of phosphorus pentoxide being available for each molecule of2,3-dibromopropanol in addition to the atoms of phosphorus required forthe desired ratio of 0.8 molecule of water per atom of phosphorus.

The reaction product is poured onto one-half its own weight of crushedice and neutralized with concentrated aqua ammonia suflicient to providea solution with a pH between 5 and 8 and a solids content of about 50wt. percent. Such solution is a substantially clear liquid, which isfurther dilutable with water to yield clear solutions.

EXAMPLE 7 218 grams of 2,3-dibromopropanol (1 gram-molecular weight) aremixed, for 1 hour at 80 C., with 1978 grams of 115% polyphosphoric acid(containing 23 gram-atomic weights of phosphorus and 0.8 molecule ofcombined water per atom of phosphorus). 180 grams of urea (3grammolecular weights) are added to the mixture which is then stirredfor 1 hour at 100 C., whereupon, 142 grams of phosphorus pentoxide(containing 2 gram-atomic weights of phosphorus) are added and the finalreaction mixture is stirred for 2 hours at 80 to 100 C.

The reaction mixture here described has a total of 25 atoms ofphosphorus per molecule of 2,3-dibromopropanol, 2 atoms of phosphorus inthe form of phosphorus pentoxide per molecule of 2,3-dibrmopropanol inaddition to the atoms of phosphorus required for the 0.8 ratio of watermolecules to phosphorus atoms, and a urea content that is less than 1molecule thereof per each two atoms of total phosphorus.

The reaction product of the above mixture is poured on crushed ice andneutralized with concentrated aqua ammonia to a pH of 5 to 8 to yield asubstantially clear solution containing approximately 50 wt. percentsolids and which is further dilutable with water.

EXAMPLE 8 A woven cotton fabric weighing 4 ounces per yard isimpregnated with a water diluted solution of the product of Example 1and then dried at 240 F. The concentration of the impregnating solutionis selected so as to result in an 11.0 wt. percent add-0n with respectto the dried fabric. The treated fabric feels soft and there is verylittle change in its color.

A sample of the fabric thus treated is subjected to the flame retardancytest specified as AATCC #34-1966, in' which a fabric specimen 10 incheslong is held vertically in a metal frame which exposes a 2 inch width ofthe fabric. The lower edge of the exposed width of fabric is ignited bya yellow Bunsen burner flame 1.5 inches long which is held in contactwith the fabric for a 12 second ignition period. The char-length of thetreated fabric, measured upwardly from its lower edge, is less than 3inches, and there is no after flame when the igniting flame is removedfrom the fabric at the end of the stated ignition period.

Results similar to those indicated above are attained when the fabric issimilarly treated with the product of Example 5.

EXAMPLE 9 A knitted fabric consisting of 10% spandex fiber and 90%nylon, by weight, is treated, as in Example 8, with an aqueous solutioncontaining equal parts, by weight, of ammonium phosphate and of thesolids content of the product of Example 1 to provide a total dry add-onof 23 wt. percent. The treated fabric has only a slightly stiffer feelthan the untreated fabric, and shows no crystallization of the treatingsubstances which are not dislodged from the fabric by shaking orrubbing. When the fabric treated with the combination of ammoniumphosphate and the product of Example 1, as here described, is subjectedto the AATCC #34-1966 flame retardancy test, there is only a 3.5 inchchar length and no after flame.

As distinguished from the foregoing, when a specimen of the same fabricis treated with a solution of ammonium phosphate alone and dried so asto have a dry add-on of 23 wt. percent, the treated fabric is stiff andhas a powdery deposit thereon which is dislodged by shaking or rubbing.Further, the fabric treated with ammonium phosphate alone so as to havea dry addon of 23 Wt. percent burns along its entire length whensubjected to the AATCC #34-1966 flame retardancy test.

EXAMPLE 10 A woven fabric composed of equal parts, by weight, ofsecondary cellulose acetate fibers and viscose rayon fibers, is treatedwith an aqueous solution of the product of Ex ample 2 and then dried soas to have a dry add-on of 13 wt. percent of the solids in such product.The thus treated fabric does not exhibit any crystallization of thetreating solids thereon and has a substantially unchanged feel. When thetreated fabric is subjected to the described AATCC #34-1966 flameretardancy test, a 4.0 inch. char length is obtained.

Reducing the dry add-on of the product of Example 2 to 10 wt. percent,the thus treated fabric of secondary cellulose and viscose rayon has achar length of 5.5 inches.

In contrast to the foregoing, the same fabric requires an 18 wt. percentdry addon of ammonium phosphate to exhibit a char length of 4.0 inches,and such add-on of ammonium phosphate results in undesirable stiffnessof the treated fabric and a powdery appearance due to crystallization.

EXAMPLE 11 An aqueous solution of the product of Example 2 is ap pliedto a knitted fabric composed of 10% spandex and nylon so as to provide,upon drying of the treated fabric, a 22 wt. percent dry add-on of thesolids in the product of Example 2. The treated knitted fabric, whensubjected to the AATCC #341966 flame retardancy test, has a char lengthof 2.5 inches and exhibits no after flame. Further, the fabric with a 22wt. percent add-on of the product according to this invention exhibitsvery little stiffening and no crystallization.

As contrasted with the foregoing, the same 10% spandex and 90% nylonknitted fabric requires a 28 wt. percent dry add-on of ammoniumphosphate in order to exhibit a char length of 5.0 inches in theidentified flame retardancy test, and even then has an after flame of 30seconds duration. Further, the fabric with a 28 Wt. percent dry add-onof ammonium phosphate exhibits substantial stiffening and a powderysurface due to crystallization.

EXAMPLE 12 An aqueous solution of the product of Example 2 is applied toa 90% triacetate-l0% nylon fabric which is then dried to provide a 3.5wt. percent dry add-on of the solids in the product of Example 2. Asurface of the treated fabric is napped. A specimen of the nappedtreated fabric is held in a plane at 45 to the horizontal with thenapped surface facing upwardly and, when such napped surface is ignited,at its center, by a match flame, no surface flash occurs. However, whenthe same napped fabric, but without the treatment thereof with the flameretardant according to this invention, is subjected to the same test,the ignition at the center of the napped surface results in an almostinstantaneous surface flash of the flame to all parts of the specimen.Thus, although the mentioned fabric having only a 3.5 wt. percent add-onof the prodnet of Example 2 will burn its entire length when subjectedto the vertical AATCC #34-1966 test, such small add-ons are neverthelesseffective as flame-retardants, particularly where it is only necessaryto eliminate the hazard of surface flash.

EXAMPLE 13 A woven fabric composed of 65 wt. percent polyester and 35Wt. percent cotton is impregnated with an aqueous solution containing 3parts, by weight, of ammonium sulfamate and 1 part, by weight, of thesolids in the product of Example 2, and then dried so as. to have a dryadd-on of 26 wt. percent. The treated fabric is soft and exhibits a 3.5inch char length in the AATCC #34-1966 vertical flame retardancy test.

As contrasted with the foregoing, the same fabric, when treated with asolution of ammonium sulfamate alone so as to have a 26 wt. percent dryadd-on of the latter, burns along its entire length when subjected tothe identified vertical flame retardancy test.

EXAMPLE 14 The tests of Example 13 are repeated with respect to a rayonnon-Woven fabric containing 20 wt. percent of acrylic resin binder. Suchfabric having a 20 wt. percent dry add-on of ammonium sulfamate aloneburns its entire length upon being subjected to the AATCC #34l966 test,but the same fabric having a 20 Wt. percent dry addon of the mixture ofammonium sulfamate and the solids of the product of Example 2, in the3:1 ratio, has a char length of 3.0 inches.

EXAMPLE .A woven cotton fabric weighing 4 ounces per yard is treatedwith ammonium sulfate alone so as'to have an 11 Wt. percent dry add-onthereof. When suchtreated fabric is subjected to the AATCC #341966 test,it exhibits an erratic flammability behavior. Thus, with a 12 secondperiod of ignition by a Bunsen burner flame, which is the standardignition period, the fabric has a 4.0 inch char length. However, if theignition period is reduced to 5 seconds, the fabric burns for its entirelength.

As contrasted with the foregoing, the same fabric provided with an 11wt. percent dry add-on of a mixture of ammonium sulfate and of thesolids of Example 2, in a 5:1 weight ratio, exhibits a 2.5 inch charlength, regardless of the duration of the ignition period, in thestandard vertical test. Further, the latter treatment provides thefabric with a softer and smoother feel than the treatment with ammoniumsulfate alone. This demonstrates how an inexpensive and relativelyineffective flame retardant salt, such as ammonium sulfate, can have itseffectiveness and reliability substantially upgraded by the additionthereto of as little as wt. percent of a product according to thisinvention.

EXAMPLEv 16 The same fabric as in Example 15 is treated with an aqueoussolution of ammonium chloride alone so as to have a 16 wt. percent dryadd on of the latter. Such addon of ammonium chloride makes the fabricquite stiff and the treated fabric burns its entire length whensubjected to the AATCC #34-1966 test.

On the other hand, the same 16 wt. percent dry add-on of a mixture ofammonium chloride and the solids of the product from Example 2, in a 4:3weight ratio, imparts to the treated fabric a feel that is only slightlystiffer than the untreated fabric. Further, the fabric treated with thedefined mixture exhibits a char length of 35 inches in the standardtest.

EXAMPLE 17 An aqueous solution of the product of Example 3 is applied toa woven fabric composed of equal parts, by Weight, of secondarycellulose acetate fibers and viscose rayon fibers so as to provide thedried fabric with a 13 wt. percent dry add-on of the solids. The treatedfabric exhibits some increase in its stiffness but no crystallization.When the treated fabric is subjected to the AATCC #34-1966 test, a 3.5inch char length is obtained.

Results similar to those indicated above are obtained when the fabric issimilarly treated with the product of Example 6.

The application of the product of Example 7 to the fabric so as toobtain a 13 wt. percent dry add-on, as indicated above, results in theattainment of similar flame retardancy, with a tendency to increase thestiffness of the treated fabric. Further, when the product of Example 7is applied to fabrics containing hydrophobic fibers, such as nylon,there is some tendency for the finish to crystalize on the surfaces ofthe non-water absorbent fibers, but this tendency is much less than thecrystallization experienced with the same add-ons of inorganic flame-rmtardant salts, such as ammonium phosphate.

EXAMPLE 18 A knit fabric composed of '90 wt. percent triacetate and 10wt. percent nylon is impregnated with an aqueous solution of ammoniumbromide and dried to provide a 23 wt. percent dry add-on of the ammoniumbromide. Al though the fabric thus treated with ammonium bromide has achar length of 4.8 inches when subjected to the AATCC #34-1966 verticaltest, the treated fabric is stiff and has a whitish crusty appearance,due to crystalliza= tion, that makes the treated fabric unacceptable forcom-- mercial use. However, when the same fabric is treated I with anaqueous solution of ammonium bromide and the product of Example 3 in theweight ratio of 9: 1, and the wt. percent dry add-on of the mixture ofsolids is 23 wt. percent, the treated fabric does not exhibit a white,crusty appearance and, moreover, its char length in the standardvertical test is only 4.0 inches. Further, the fabric is notunacceptably stiff. Thus, it will be seen that the addition'ofrelatively small proportions of a flame retardant according to thisinvention to an inorganic salt, such as ammonium bromide, can correctundesirable characteristics of the latter as an inexpensive flameretardant.

EXAMPLE 19 Aqueous solutions of the product of Example 4 are applied towoven cotton fabrics of various weights and constructions, and are foundto make such fabrics fire resistant according to the AATCC #34-1966 testwith dry add-ons of the solids ranging from 9 to 13 wt. percent. Thelower add-ons of the fire retardant are effective to impart fireresistance, that is, to prevent burnin of the fabric specimen along itsentire length, in the case of the relatively heavier fabrics, whereasthe larger concentra tions (13 wt. percent add-on) are required for thelighter fabrics, such as, 4 ounce per yard fabrics.

It should be noted that the previously mentioned am 'monium salt of2,3-dibromopropylphosphoric ester is only sparingly soluble in water andis a costly compound in comparison with such substances as ammoniumphosphate and ammonium sulfamate. The foregoing is true because therelatively costly 2,3-dibromopropanol is a major pro-= portion of thementioned compound. However, with the products according to thisinvention, the weight propor: tion of dibromopropanol can be greatlyreduced, as is apparent from the foregoing examples, while retainingmost of the advantages of the unmodified ester. Further, the productsaccording to this invention may be admixed with inorganic flameretardant salts, to improve the properties of such inexpensive salts asin certain of the. examples. However, it is to be understood that theproducts of this invention are not mere mixtures of the normal di--bromopropylphosphoric ester with ammonium phosphate or ammoniumpolyphosphate, although it is possible that minor amounts of theselatter salts may be present in the reaction products due to sidereactions. An indication of the fact that the reaction productsaccording to the invention are true chemical compounds and not meremiX-= tures is found in their solubility in water which is far higherthan that of the unmodified dibromopropylphosphoric ester. This enhancedsolubility in water, which in creases with the proportion of pound, Ibelieve to be due to the phosphorus in the compresence of a pluralitygroups in the molecule.

As the number of such groups lncreases, the water-soluentire moleculeincreases, particularly in the or spirit of the invention. What isclaimed is:

erature in the range from The reaction product obtained by mixing, at atemapproximately 80 C., to

approximately 110 C., 2,3-dibromopropanol, phosphorus pentoxide in anamount suflicient to provide therein from 4. A flame retardant accordingto claim 3, in which the amount of water in which said reaction productis dissolved is suflicient to provide a solids content therein of from50 to 55 wt. percent.

1y of by mixing, mately 80 propanol, sufiicient 115% thereof in therange from 6. 1y of 5 to 8. A, water-soluble flame retardant consistingessentialan. aqueous solution of the reaction product obtained bymixing, at a temperature in the range from approximately C. toapproximately 110 C: 2,3-dibromopropanol, suflicient 115% polyphosphoricacid '.0 provide 6 atoms of phosphorus per molecule of2,3-dibromopr0pa-- nol, suflicient urea to provide 3 molecules thereofper molecule of 2,3-dibromopropanol and suflicient phosphorus pentoxideto provide 2 atoms of phosphorus therein per molecule of2,3-dibromopropanol, and suflicient ammonia in said solution to providea pH thereof in the range from 5 to 8.

7. A water-soluble flame retardant consisting essentially of an aqueoussolution of the reaction product obtained by mixing, at a temperature inthe range from approximately 80 C. to approximately 110 C.,2,3-dibromopropanol, sufiicient 115% polyphosphoric acid to provide 18atoms of phosphorus therein per molecule of said 2,3-dibromopropanol,2-molecules of urea per molecule of said 2,3-dibromopropanol andsuificient phosphorus pentoxide to provide 2 atoms of phosphorus thereinper molecule of said 2,3-dibromopropanol, and sufficient ammonia in saidsolution to provide a pH thereof in the range from 5 to 8.

8. A Water-soluble flame retardant consisting essentially of an aqueoussolution of the reaction product obtained by mixing, at a temperature inthe range from approxi mately 80 C. to approximately 110 C.,2,3-dibromopropanol, suflicient phosphoric acid to provide 1 atom ofphosphorus therein per molecule of said 2,3-dibromopropanol, sufiicienturea to provide 2 molecules thereof per molecule of said2,3-dibromopr0panol and phorus therein per molecule of said2,3-dibromopanol, and sutficient ammonia in said solution to provide apH thereof in the range from 5 to 8.

9. A water-soluble flame retardant consisting essential- 1y of anaqueous solution of the reaction product obtained by mixing, at atemperature in the range from approximately 80 C. to approximately C.,2,3-d1blOI110pIO panol, sutficient phosphorus pentoxide to provide 3.5atoms of phosphorus therein per molecule of said 2,3-di' bromopropanoland suflicient free water to provide 2 molecules thereof per molecule ofsaid 2,3dihromopropanol, and suificient ammonia in said solution toprovide a pH thereof in the range from 5 to 8.

References Cited UNITED STATES PATENTS 3,283,013 11/1966 Rimmer s,260--933 X CHARLES B. PARKER, Primary Examiner A. H. SUTTO, AssistantExaminer U.S. c1. X.R. 106-15 FP; 117-137; 260-924, 933, 980

